Pressurized dispensing containers comprising a viscous foamable product to be dispensed as well as a pressurizing fluid have been in widespread use for a variety of applications. A well-known application are sprayable mounting foams, more specifically polyurethane foams, used in industrial applications as well as by hobbyists for insulating and sealing purposes on windows and doors.
Pressurized dispensing containers of this type typically have a valve arranged on their upper end via which the content of the pressurized dispensing container is discharged when said valve is actuated. On this valve, an adapter is fixed by means of a lever part. This lever part preferably is releasably connected to said valve, for instance by means of a screw connection. This adapter furthermore comprises a dip tube which at its proximal end thereof is connected to the lever part and is adapted for conveying the formed foam towards its distal end where it is then dispensed.
The problem arising with such pressurized containers comprising a pressurized foamable solution which is converted into a foam when leaving the container at the height of said valve, especially for mounting foams such as polyurethane foams which harden quickly when coming into contact with the environment, is that, because the foam when being out of the container hardens under the influence of the environmental air, the continued use of the content of the container is prevented. Especially for private use, this is a big problem since this often only requires small amounts to be used at a given time, such that initially only a relatively small portion of the container content is consumed and the remaining contents of the container after a certain storage time cannot be used anymore. This spoilage is economically as well as environmentally annoying.
At present, already different tip seals for adapters for pressurized containers containing a viscous foamable solution have been developed to solve the abovementioned problem and to provide the contents of the container fresh and usable as long as possible.
In DE 10 2004 003 263 for instance, a spray system for dispensing aerosol substances including polyurethane foam for window and door frames is disclosed, wherein said spray system has a cylindrical tube with a cap on threaded end with an aperture accommodating a central stopper. The cylindrical tube has a spiral ridge forming a coarse screw thread on its outside diameter, engaging with a sleeve on the end of a reservoir container. The tube is open at its base end and there is a central cylindrical stopper held on three equispaced struts. The end of the stopper fits into a central aperture in a cap with a female thread engaging a male thread on the end of the tube. There is a flange between the coarse thread and the thread for the cap.
In WO 2012/115842, a dispensing device for dispensing compressed fluid from a can through a valve stem of the can. The dispensing device contains a hollow tube defining a channel there-through. A connector is provided defining a conduit there-through that is in fluid communication with the channel of the hollow tube. A plug is located in the channel of the hollow tube that is able to move in the channel of the hollow tube and seal the hollow tube from fluid flow when pressed towards the dispensing end of the hollow tube. A sealed port is located between the inside and the outside of the dispensing device and a flexible and inelastic extension piece is attached to the plug and extends through the channel of the hollow tube and optionally extends through the conduit of the connector then out from the dispensing device through the sealed port and capable of attaching to a can to which the dispensing device is connected.
Both dispensing systems as disclosed above however suffer from the disadvantage that the closure element for closing off the partially open distal end of the hollow dip tube through which the fluid passes when being dispensed, is located inside and extends substantially throughout the dip tube forming a hurdle within this dip tube. This forms a hurdle for fluids to be dispensed that easily polymerize when coming into contact with the outside air, which is for instance the case with polyurethane foam coming into contact with the humidity of the outside air. When such fluids stick to this closure element and polymerize there when coming into contact with the outside air, this hardened substance hinders or even completely blocks passage of further fluid to be dispensed throughout the dip tube. In the latter case, the unconsumed residue of the substance intended to be dispensed even becomes unusable. Such dispensing systems are thus subjected to the risk of the dip tube becoming clogged at the height of this closure element.
It is furthermore not clear how clogged dip tubes of this type of dispensing systems can be cleaned. In each case, the flexible and inelastic extension piece that extends through the channel of the hollow tube of the dispensing system as disclosed in WO 2012/115842 is not rigid enough to break hardened PUR foam obstructing the channel of the hollow tube.
A further disadvantage of such kind of dispensing systems having a closure element inside the dip tube is that these are not easy to manufacture and require a complex production mould. Especially in WO 2012/115842, a complex dispensing device composed out of a lot of parts is disclosed.
There consequently exists a need to provide a tip seal for an adapter that is configured to be connected to a pressurized container comprising a viscous foamable solution that is converted into foam when leaving said container, said tip seal being less sensitive to obstructions, simple, easy and cheap to manufacture and easy to clean.